Condensation reduction and management systems in a gas flow delivery system

ABSTRACT

Condensation management techniques for a gas flow delivery system. The techniques include providing a radiant barrier associated with patient circuit and/or a patient interface, providing a water trap and/or an absorbent insert in the patient interface device, or a combination of these techniques. The radiant barrier prevents condensation from forming in the patient circuit and/or the patient interface. The water trap and absorbent insert in the patient interface control condensation that reaches or forms in the interior of the patient interface to prevent it from interfering the user of the gas delivery system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional under 35 U.S.C. §120 of U.S. patentapplication Ser. No. 11/300,052, filed Dec. 14, 2005, now U.S. Pat. No.8,757,150, which claims priority under 35 U.S.C. §119(e) fromprovisional U.S. patent application No. 60/637,339, filed Dec. 17, 2004,the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a system for isolating, controlling, orreducing condensation in a patient circuit or in a patient interface ina gas flow delivery system.

2. Description of the Related Art

Gas flow delivery systems are used to deliver a flow of gas to an airwayof a subject. Such systems are typically used in the medical field todeliver gas to a patient. Examples of gas flow delivery systems in themedical field include a ventilator or respirator, which replaces orsupplements a patient's respiration, and a pressure support system,which provides a flow of gas to an airway of a patient at an elevatedpressure to treat a medical disorder, such as obstructive sleep apnea(OSA). Pressure support systems include, but are not limited tocontinuous positive airway pressure (CPAP) devices, which delivers aconstant positive pressure to the airway of a patient over multiplerespiratory cycles, and variable pressure devices where the pressure ofthe flow of gas delivered to the patient is variable.

Variable pressure devices include auto-titrating devices that arecapable of changing a base pressure or pressure profile delivered to thepatent based on a monitored condition of the patient. Other variablepressure devices change the pressure of the flow of gas during arespiratory cycle. These devices include the following: a proportionalassist ventilation (PAV®), a proportional positive airway pressure(PPAP®) device, a C-Flex™ device, a Bi-Flex™ device, and a BiPAP® devicemanufactured and distributed by Respironics, Inc. of Pittsburgh, Pa. TheBiPAP device is a bi-level pressure support system in which the pressureprovided to the patient varies with the patient's respiratory cycle sothat a higher pressure is delivered during inspiration than duringexpiration.

A typical gas flow delivery system comprises a pressure/flow generatingsystem that produces a flow of gas for delivery to a patient and asystem for communicating the flow of gas to the patient. The lattersystem typically includes a flexible conduit having one end coupled tothe pressure/flow generating device and a second end portion thatcouples to an airway of patient through a patient interface. Theconduit, which is also referred to as a patient circuit, carries theflow of gas from the pressure generating device during operation of thesystem. The patient interface device, typically in the form of a nasal,oral, or nasal/oral mask, is coupled to the second end portion of theconduit to communicate the flow of gas from the patient circuit to theairway of the patient.

Heated humidifiers have been developed for use with gas delivery systemdevices to humidify the gas supplied to the patient. A typicalhumidifier comprises a heated water reservoir connected in series withthe delivery conduit between the flow generator and the patientinterface. As the humidified gas moves through the patient circuit fromthe humidifier to the patient interface, condensation or rainout mayfrom in the patient circuit or in the patient interface device.Condensation will occur if the gas leaving the humidifier is at asaturation level higher than that required to attain saturation at thelower temperature of the patient interface.

Condensation may also build up on the inner surface of the patientcircuit and/or the patient interface. The formation of condensation inthe patient circuit is not limited to the use of heated humidifiers.Condensation may also form whenever the ambient temperature is colderthan the gas temperature of the patient circuit. Condensation may evenform in the patient circuit without any form of humidification present,such as in winter.

Condensation in the patient circuit and/or patient interface isundesirable for several reasons. First, liquid in the patient circuitmay reach the patient, where it could drip on the patient's face. Moistareas are also more prone to formation of bacteria. Additionally, gasflowing through any accumulated condensation may generate an annoyinggurgling sound. To remove the condensation it is necessary for thepatient or caregiver to periodically disconnect the patient from the gasflow/pressure generator, for example by removing the mask from the faceor disconnecting the patient circuit from the mask or gas flow/pressuregenerator so that the condensed water can be drained. This process isdisruptive and may interfere with the patient's therapy.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to providetechniques for isolating, controlling, or reducing condensation in apatient circuit and patient interface. This object is achieved accordingto one embodiment of the present invention by providing a patientcircuit that includes a conduit having a first end portion, a second endportion, and a lumen defined therein from the first end portion to thesecond end portion. A radiant barrier is associated with the conduitsuch that the radiant barrier is disposed between an ambient environmentand the lumen. The radiant barrier is a low emissivity material thatreduces heat loss from the conduit due to radiant energy. By reducingradiation heat loss from the conduit, the gas flow in the conduit is notcooled as much as in current systems, which use only an insulation layerto prevent heat loss due to conduction. By reducing the amount ofcooling, condensation is reduced.

In another embodiment of the present invention, this object is achievedby providing a patient interface having a shell and an insert member.The shell wall and insert member are sized, configured, and disposedrelative to one another such that a gap is defined between the wall ofthe insert member and a wall of the shell. The gap is positioned suchthat water entering the interface from the patient circuit is preventedfrom reaching the patient, but collects in this space. This preventswater or the possible intrusion of water into the patient's airway whenthe mask is donned by the user. The insert also creates an insulationlayer within the interface, much like a double glass window on a home.The warm and humid gas fills the gap between the shell and theattachment, forming an insulating layer to eliminate condensation on theinsert member wall facing the patient. Instead, any condensation thatmay form will do so on the wall of the shell, where it is trapped in thegap between the shell and the insert member.

In yet another embodiment, this object is achieved by providing a systemfor delivering a breathing gas to a patient that includes a gas flowgenerating device that produces a flow of gas, a conduit that carriesthe flow of gas from the gas flow generating device during operation ofthe system, and a patient interface coupled to the conduit. In addition,an absorbent material is disclosed in the patient interface. In apresently preferred exemplary embodiment of the invention, the absorbentinsert comprises a super-absorbent polymer material disposed inside aporous wicking material, such as cloth or paper. The super-absorbentpolymer material can absorb water up to 300 times the volume of theabsorbent insert. After use, the saturated absorbent insert may be airor oven dried and re-used. The absorbent insert is preferably largeenough so that the absorbent insert may not accidentally invade thenasal cavity.

These and other objects, features, and characteristics of the presentinvention, as well as the methods of operation and functions of therelated elements of structure and the combination of parts and economiesof manufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. It is to be expressly understood, however, that thedrawings are for the purpose of illustration and description only andare not intended as a definition of the limits of the invention. As usedin the specification and in the claims, the singular form of “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a gas flow generating system thatincludes a patient circuit having a radiant barrier according to theprinciples of the present invention;

FIG. 2 is a partial cut-away perspective view of the patient circuit ofFIG. 1;

FIG. 3 is a cross-sectional view of the patient circuit of FIG. 2;

FIGS. 4-7 are cross-sectional views of other embodiments for a patientcircuit having a radiant barrier according to the principles of thepresent invention;

FIG. 8 is a rear perspective view of a first exemplary embodiment of apatient interface having a water trap according to the principles of thepresent invention;

FIG. 9 is front perspective view of the patient interface of FIG. 8;

FIG. 10 is an exploded view of the patient interface of FIG. 8;

FIGS. 11 and 12 are perspective views of a water trap insert in thepatient interface of FIG. 8;

FIGS. 13 and 14 are cross-sectional views of the patient interface ofFIG. 8 showing the condensation collection technique;

FIG. 15 is a rear perspective view of a second exemplary embodiment of apatient interface having a water trap according to the principles of thepresent invention;

FIGS. 16 and 17 are partially exploded front and rear perspective views,respectively, of the patient interface of FIG. 15;

FIGS. 18 and 19 are perspective views a water trap insert in the patientinterface of FIG. 15;

FIGS. 20 and 21 are cross-sectional views of the patient interface ofFIG. 15 showing the condensation collection technique;

FIG. 22 is a cross-sectional view of the patient interface of FIG. 12with an additional o-ring;

FIG. 23 is a cross-sectional close-up view of the o-ring in the patientinterface of FIG. 22;

FIG. 24 is a cross-sectional perspective view of a third embodiment fora patient interface having a water trap according to the principles ofthe present invention;

FIGS. 25 and 26 are perspective views a water trap insert for thepatient interface of FIG. 24;

FIG. 27 is a rear perspective view of a patient interface that includesan absorbent insert according to the principles of an exemplaryembodiment of the present invention;

FIGS. 28 and 29 are a cross-sectional end and side views, respectivelyof an exemplary embodiment of the absorbent insert of FIG. 27; and

FIGS. 30 and 31 are cross-sectional end and side views, respectively, ofanother embodiment for an absorbent insert.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring first to FIGS. 1-3, a gas flow delivery system 10 fordelivering a flow of gas to an airway of a patient is illustrated. Gasflow delivery system 10 comprises a pressure generating device 12 thatproduces a flow of gas and an optional humidifier 14 coupled to anoutlet 16 of the pressure generating device 12. A gas delivery conduit,which is also referred to as a patient circuit, 18 is coupled to theoutlet of the humidifier. Of course, if the humidifier is omitted, thepatient circuit would be coupled to the outlet of the gas flowgenerating device.

Pressure generating device 12 is any conventional ventilation orpressure support system. Examples of such systems include, but are notlimited to: a ventilator, continuous positive airway pressure (CPAP)device, or a variable pressure device, e.g. an auto-titrating device,proportional assist ventilation (PAV®) device, proportional positiveairway pressure (PPAP®) device, C-Flex™ device, Bi-Flex™ device, or aBiPAP® device manufactured and distributed by Respironics, Inc. ofPittsburgh, Pa., in which the pressure provided to the patient varieswith the patient's respiratory cycle so that a higher pressure isdelivered during inspiration than during expiration, or other pressuresupport device.

Patient circuit 18 has a first end portion 20 operatively coupled tohumidifier 14 and a second end portion 22. A lumen 23 is defined throughthe patient circuit from the first end portion to the second end portionso that a flow of gas is carried from the humidifier or the pressuregenerating device to the patient during operation of the gas flowgenerating system. A patient interface 24, which is typically a mask, iscoupled to second end portion 22 of patient circuit 18. In theillustrated exemplary embodiment of the present invention, patientinterface 24 is a nasal mask. It is to be understood, however, thatpatient interface 24 can include a nasal mask, nasal pillows, trachealtube, endotracheal tube, or any other device that communicates a flow ofgas from the patient circuit to the airway of the patient.

It is to be understood that various components may be provided in orcoupled to the patient circuit. For example, a bacteria filter, pressurecontrol valve, flow control valve, sensor, meter, pressure filter,humidifier, and/or heater can be provided in or attached to the patientcircuit. Likewise, other components, such as muffler and filters can beprovided at the inlet of the pressure generating device.

Gas flow delivery system 10 shown in FIG. 1 is a single-limb system,meaning that the patient circuit includes only one gas delivery conduit20 connecting the patient to the pressure generating device. In asingle-limb system, exhaust vent 25 is provided in the patient conduitfor venting exhaled gasses from the system. The exhaust vent can beprovided on the patient interface device and/or on the patient circuitand can have a wide variety of configurations depending on the desiredmanner in which gas is to be vented from the pressure support system.

The present invention also contemplates that the gas flow generatingsystem can be a two-limb system, which includes a delivery conduit andan exhaust conduit operatively connected to the airway of the patient. Akey difference between a single-limb system and a two-limb system isthat in a two-limb system, there is an exhaust conduit that carriesexhaust gas from the patient. An exhaust valve is also typicallyprovided at the end of the exhaust conduit distal from the patient. Theexhaust valve is normally actively controlled to maintain a desiredlevel of pressure in the system, which is commonly known as positive endexpiratory pressure (PEEP). This is accomplished by controlling the flowof exhaust gas from the otherwise closed system.

Patient circuit 18 includes a conduit 26, which is preferably a flexibleconduit and a radiant barrier 28. Conduit 26 can be any conventionalconduit, such as the 6 foot smooth lumen tubing manufactured by the HTHCOMPANIES, Inc. or SMOOTH-BOR and sold by RESPIRONICS, Inc. Whileconduit 26 is shown as being a corrugated tubing, it is to be understoodthat conduit 26 could be a cylindrical tubing. Conduit 26 can also haveany other shape, i.e., non-cylindrical, so long at it accomplishes thefunction of carrying a flow of fluid from one place to another. Itshould also be understood that coupling members can be provided at theends of the conduit 26 for coupling the patient circuit to the pressuregenerating device, patient interface, or any other desired component andthat these coupling members can have any desired configuration orfeatures.

It is should be clearly understood that heat transfer can take place inthree forms: 1) conduction, which is by means of molecular agitationwithin a material, without any motion of the material as a whole, 2)convection, which is heat transfer by mass motion of a fluid when theheated fluid is caused to move away from the source of heat carryingenergy with it, and 3) radiation, which is heat transfer by the emissionof electromagnetic waves that carry energy away from the emittingobject. It is known to prevent heat loss from a patient circuit byproviding an insulating material around the conduit. See, e.g., U.S.Pat. No. 5,623,922. While this prevents heat loss due to convection, itdoes not address heat loss due to radiation. By being formed from a lowemissivity material, radiant barrier 28 specifically attempts to reduceor eliminate heat transfer between the interior of the conduit and theambient environment due to radiation.

In an exemplary embodiment of the present invention, the radiant barrieris disposed on an external surface 32 of conduit 26. In one embodiment,this is accomplished by providing a foil as the radiant material, wherethe foil is coupled to the conduit by being wrapped around the conduitor is in the form of a flexible sheath into which the conduit isinserted. It is to be understood that radiant barrier 28 can be coupledto conduit 18 in any conventional manner, such as with hook and loopfasteners, a zipper, straps or any other suitable fastening means. Forexample, the present invention contemplates that the radiant barrier canbe provided in a sleeve or sheath, that has a lengthwise zipper or hookand loop fastener, so that the radian barrier is wrapped around theconduit and then coupled to the conduit by closing the zipper orapplying the hook and loop fasteners to one another. Providing radiantbarrier 28 on the external surface of the conduit can also beaccomplished by providing a low emissivity coating disposed on thesurface of the conduit. Any conventional coating technique, such asdipping or spray, can be used to apply the radiant barrier coating onthe conduit.

In the illustrated exemplary embodiment, radiant barrier 28 surrounds atleast a portion of the external surface of delivery conduit 26. Radiantbarrier 28 is formed from a radiant barrier material having a lowemissivity, such as a reflective foil, to reduce heat loss from lumen 23due to radiant energy. Preventing heat loss prevents condensation fromforming on an interior surface 30 of conduit 26 by preventing the air inthe tube from cooling to the point where it reaches its dew point.

The radiant barrier provides a reflective surface that keeps a highpercent of the radiant energy from reaching the interior surface of theinsulated body. Radiant barrier fabric is found in protective clothinglike that used by firemen or space suits. An example of a fabricsuitable for the radiant barrier is the CROSSTECH® S/R fabric. Ametalized fabric, such as an aluminized polymer fabric, or an analuminized polymer film is also highly effective as a radiation barrier.Examples of such fabrics include the ClearDome Solar Thermal BarrierFabric.

A further embodiment of the present invention contemplates providing athermal insulation layer 34 over radiant barrier 28. See FIG. 4.Insulating layer 34 is formed from an insulating material having a lowthermal conductivity, such as an insulating man-made material comprisingpolyester fibers, although any suitable insulating material formed fromman made and/or natural fibers could be used. An example of a suitableinsulating material is the DuPont® Thermolite® Active material, which isa performance fabric employing a hollow-core fiber technology in whichair is used as the insulating material.

The present invention also contemplates providing a thermal insulationlayer 34′ disposed between radiant barrier 28′ and an external surface32 of conduit 26. See FIG. 5. Although not shown, another radiantbarrier, i.e., low emissivity material, can be provided over thermalinsulation layer 34′ to further reduce heat transfer. Further layeringof thermal insulation materials and radiant barriers can be provided.

A still further embodiment of the present invention contemplatesproviding a radiant barrier 28′ on an interior surface 36, i.e., asurface facing lumen 23, of conduit 26. See FIGS. 6 and 7. An additionallayer of thermal insulation 34′ can be provided over external surface 32of the conduit. See FIG. 7. Of course, further layers of the radiantbarrier and/or the thermal insulation can be provided around theconduit. As with the previous embodiment, the present inventioncontemplates that the radiant barrier can be disposed on or proximate tothe interior surface of the conduit using any conventional technique,such as spraying or dipping to coat the radiant barrier on the conduitor by mechanically fastening the radiant barrier to the conduit. Thepresent invention also contemplates that the conduit itself, includingthe interior and/or exterior surface, can be formed from a lowemissivity material, so that the radian barrier is integral with thematerial defining the conduit.

The present invention contemplates that the radiant barrier can beapplied to selected portions of the patient circuit or over the entirepatient circuit, i.e., from the outlet of the humidifier 14 and/orpressure generating device, to the inlet of the patient interfacedevice. The present invention also contemplates that the radiant barrierneed not be disposed entirely around the conduit, as shown in thefigures, but can be disposed around only a portion of the conduit.

Referring now to FIGS. 8-14, a first exemplary embodiment of a patientinterface 42 having a water trap according to the principles of thepresent invention is illustrated. Patient interface 42 includes a maskfaceplate or shell 48 and a mask seal 50, also typically referred to asa cushion, for contacting the facial surface of a patient. Shell 48includes an opening 52, as perhaps best shown in FIG. 9, thatcommunicates with a mask elbow 54 leading to the patient circuit.Patient interface 42 also includes an insert member 44 disposed in achamber defined by the shell and/or the seal. The present inventioncontemplates that insert member 44 is either permanently coupled to theshell and/or seal or is electively attachable to either of thesecomponents. In addition, the present invention contemplates thatmounting components can be used to couple the insert member to the shellor seal so that the insert member is not “directly” attached to eitherof these components. In the illustrated embodiment, a retaining ring 51is provided that attaches seal 50 and insert member 44 to shell 50 byfitting into a groove defined in the shell.

Insert member 44 is preferably a contoured cup-shaped member having aninner surface 56 facing the patient and an outer surface 58 facing aninner surface 60 of shell 48. Outer surface 58 is substantiallycontoured to generally correspond to the shape of inner surface 60 ofshell 48. When insert member 44 is in position, a gap 62 is formedbetween outer surface 58 of the insert member and the inner surface 60of the shell. Gap 62 functions as a reservoir to segregate or collectcondensation C so that the condensation does not reach the patient. Aport 61 is defined in shell 48 that communicates gap 62 with an areaexternal to the shell. Port 61 provides a drainage point so thatcondensation collecting in gap 62 can be removed. Of course, a cap (notshown) can be disposed over the external opening of port 61 to seal thewater trap, i.e., prevent fluid from existing port 61.

In this illustrated exemplary embodiment, insert member 44 issubstantially triangularly-shaped as is shell 48 and has an opening 64to allow gas from the patient circuit to pass into a chamber 65 definedby the insert and seal. In an exemplary embodiment, openings 63 and 64are substantially aligned. Condensation forming on a wall of the patientcircuit, i.e., a wall of elbow 54, will travel along the wall of theelbow and enter the shell through opening 63. Because opening 64 ofinsert member 44 is offset from opening 63 over the entire periphery ofthese openings, condensation will not enter opening 64, but will passbetween openings 63 and 64 into chamber 62.

It should also be noted that gas that is typically warmer than theambient environment will occupy gap 62. As a result, it is possible thata temperature difference will exist between gap 62 and the ambientenvironment, which will result in condensation forming on surface 60 ofshell 48. Of course, this condensation will be trapped in gap 62.However, there will be little temperature differential between the gasin gap 62 and the gas in chamber 65. As a result, it is unlikely thatcondensation will form on inner surface 56 or insert member 44 or on theinner surface of seal 50, which is where condensation is most undesired.It can thus be appreciated that the water trap configuration of thepresent invention not only helps contain any condensation that forms inthe patient circuit or the patient interface, but also helps prevent anycondensation from forming on any surface that directly faces the surfaceof the patient.

FIGS. 15-21 show a second exemplary embodiment of a patient interface 68having a water trap according to the principles of the presentinvention. Patient interface 68 is similar in many respects to thepatient interface shown in FIGS. 8-14; the main differences being in theconfigurations of a mask shell 70 and insert member 66. Morespecifically, in this embodiment, mask shell 70 includes an adjustableforehead assembly 72 that is coupled to the mask shell and movesrelative to the mask shell, as generally indicated by arrow A in FIG.20. The forehead assembly also includes a moveable forehead pad support74 that moves relative to a forehead arm 76, as indicated by arrow B inFIG. 20. A pad 78 is provided on the forehead pad support 74, and a sealor cushion 80 is attached to shell 70. Insert member 66 has a moreplanar wall than in the previous embodiment. In this embodiment aretaining ring 77 is provided on the outer perimeter of the shell andseal. The retaining ring includes tabs 79 that snap over an edge of theshell to sandwich the edge of the seal between the retaining ring andthe shell.

The point to be understood and appreciated is that the present inventioncontemplates that the various components of the patient interface canhave a variety of sizes, shapes, and configurations. For example, anysuitable technique can be used to couple the shell, seal, and insertmember to one another in either a fixed or separable manner. Inaddition, other features associated with patient interface devices, suchas adjustable forehead supports, headgear connectors, and headgear, canbe used conjunction with the water trap condensation managementtechnique.

FIGS. 22 and 23 illustrate a patient interface 82 that is generallysimilar to patient interface 68. However, patient interface 82 includesan o-ring 84 provided along the outer perimeter of insert member 66.O-ring 84 helps to prevent leakage of condensation from gap 62′ intochamber 65′. It should be noted that this o-ring leak prevention featurecan be provided on any of the patient interface embodiments of thepresent invention.

FIGS. 24-26 illustrate a third embodiment of a patient interface 90having a water trap according to the principles of the presentinvention. In this embodiment, an insert member 92 is provided to form awater trap gap 94 between the insert member and a wall of shell 96.Insert member 92 is shaped such that the wall or surface of the insertmember that faces an interior surface of the shell does not correspondto the shape of the shell. As a result, gap 94 has a relatively largervolume as compared to the other embodiments.

The present invention contemplates providing a thermal insulator insertin the patient interface. In an exemplary embodiment, the insulatorinsert has a configuration corresponding to the insert members of theprevious embodiments. However, the thermal insulator insert need notprovide a gap between it and the mask shell wall. For example, theinsulator insert can have a shape that substantially matches the innersurface of the shell to provide a thermal insulation barrier in the maskshell that abuts the inner surface of the shell. Of course, theinsulator insert can include a gap between it and the wall of the shell.The insulator insert is preferably vacuum formed from a closed cellfoam, such as polystyrene foam and may be disposable.

The insulator insert eliminates condensation by reducing the temperaturedifference between the delivery gas and the ambient environment. Theinsulator insert creates an air filled barrier to reduce heat loss andlower condensation. The shell material, most typically polycarbonate,has a higher thermal conductivity value than the foam insulator insert.The thermal conductivity of a material is a measure of the ability totransmit heat through the material. The typical value of thermalconductivity for polycarbonate is at 1.44 w/m-k, while the value forpolystyrene is 0.202 w/m-k. Polystyrene foam has a lower thermalconductivity value. In general, the foam insulator insert can reduceheat loss by two-fold.

In yet another embodiment of the present invention, the insulator insertis formed from a low emissivity material to provide a radiant barrier inthe shell. The present invention also contemplates providing both athermal insulator and a radiant barrier in the patient interface. Thepresent invention also contemplates forming the shell of the patientinterface from a low emissivity material so that the walls of thepatient interface, more specifically, the wall of the shell, form aradiant barrier to prevent heat loss from the chamber in the shell tothe ambient atmosphere due to radiation of heat.

Referring now to FIGS. 27-31, another embodiment of the presentinvention is illustrated. In this embodiment an absorbent insert 100 islocated within a chamber defined in a patient interface 102. Preferablythe absorbent insert is situated where condensation may form or pool anddoes not block a patient circuit connection opening 104 defined in themask shell. Absorbent insert 100 preferably comprises an inner absorbentmaterial 106 disposed within an outer cover 108. Preferably, innerabsorbent material 106 is a super-absorbent polymer, such as apolyacrylate absorbent, which is often used in the manufacture ofdisposable diapers, but may also be any other suitable absorbentmaterial such as cotton. Outer cover 108 is preferably a porous, liquidpermeable, material, such as cloth, paper, coffee filter material, teabag material, or any other suitable material. FIGS. 27-29 illustrate anembodiment in which absorbent insert 100 may be freely manipulated and“dropped in” the interior body portion of the patient interface. Thepresent invention also contemplates that outer cover 108 is formed froman absorbent material.

It is to be understood that the present invention contemplates providingthe absorbent insert at other areas of the patient interface and/orpatient circuit, such as at the mask shell, mask cushion, the deliveryconduit, or the swivel elbow to absorb and isolate condensed water.Alternatively, a secondary component, which contains the absorbentinsert, may be connected between the mask and the patient circuit.

In another embodiment illustrated in FIGS. 30 and 31, an absorbentinsert 100′ is shown having a flexible/formable inner member 110provided in the interior of absorbent outer cover 108. Flexible/formablemember inner member 110 is preferably formed from a moldableshape-retaining material, such as aluminum, copper, brass, a shapememory alloy, or any other shape-retaining metals or alloys or athermoplastic, such as polycarbonate, polyurethane, polyethylene, orother plastic compounds which allow the absorbent insert to bemanipulated and shaped to fit various sizes and styles of patientinterfaces. Absorbent insert 100′ is placed behind the seal and is heldin place by the flexible/formable inner member 110. Absorbent outercover 108 is formed of a durable material to prevent rupture caused bythe flexible/formable inner member. The material for cover 108 may be awoven natural fabric such as cotton, silk, wool, burlap or can be a manmade fiber such as polyester, rayon or nylon or may be a blend such ascotton-polyester blend. The seams in cover 108 are sewn or heatsealed/adhesive bonded. Alternatively, the inner member may bepre-formed or molded so that it can be inserted into a cavity or otherfeature custom-molded into a specific mask. In still another embodiment,the absorbent outer cover itself may be formed from a formable, pliablematerial which provides rigidity to the absorbent insert itself.

It should be understood that the present invention contemplates usingeach of the condensation reduction and management techniques alone or incombination with one or more of the other condensation reduction andmanagement techniques.

Although the invention has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the invention is not limitedto the disclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements that are within the spirit andscope of the appended claims. For example, it is to be understood thatthe present invention contemplates that, to the extent possible, one ormore features of any embodiment can be combined with one or morefeatures of any other embodiment.

What is claimed is:
 1. A patient interface comprising: a shell having afirst shell surface, a second shell surface opposite the first shellsurface, a first shell opening, and a second shell opening; an insertmember having a first insert surface facing the first shell surface anda second insert surface adapted to face a user responsive to the patientinterface being worn by the user, wherein a gap is defined between thefirst insert surface and first shell surface; an adjustable foreheadassembly comprising a movable forehead support pad and a forehead arm,wherein the forehead pad moves relative to the forehead arm, and whereinthe adjustable forehead assembly is coupled to the shell and movesrelative to the shell; and a water absorbent material disposed in thegap.
 2. The patient interface of claim 1, wherein the insert memberincludes a first insert opening defined therein, and wherein the firstinsert opening and the first shell opening are substantially aligned. 3.The patient interface of claim 1, further comprising a cushion coupledto the second shell surface.
 4. The patient interface of claim 1,further comprising a port defined in the shell communicating the gapwith an area external to the shell.
 5. The patient interface of claim 1,wherein the insert is removably attached to the shell.
 6. A patientinterface comprising: a shell having a first shell surface, a secondshell surface opposite the first shell surface, a first shell opening,and a second shell opening; an insert member having a first insertsurface facing the first shell surface and a second insert surfaceadapted to face a user responsive to the patient interface being worn bythe user, wherein a gap is defined between the first insert surface andfirst shell surface; a chamber having a chamber surface facing thesecond insert surface; and an O-ring, configured to prevent leakage ofcondensation from the gap into the chamber, disposed along a perimeterof the insert member.